A progressive university students' group posted a screenshot of their email to Thae Yong-ho, a former North Korean diplomat who defected to South Korea in 2016, on Facebook Tuesday. Captured from @univjinbo's Facebook account

By Jung Da-min

Thae Yong-ho. Korea Times file

Thae Yong-ho, a high-ranking North Korean defector who has backed sanctions on North Korea, called off attending a public event early this week after receiving a threatening letter from an online community for progressive students. The letter warned him to stop "activities hindering reunification" of the two Koreas or the community's members will move to "arrest" him. Such criticism is not unusual for Thae, who fled to Seoul in August 2016 while serving in the United Kingdom as North Korea's deputy ambassador. He has been a target of harsh words from progressive activists who support the Moon Jae-in administration's North Korea-friendly policies. But it is the first time he has canceled an appearance following criticism. The community posted the letter's full text on its Facebook account Tuesday, the day it sent the letter to the defector and the cancelation took place. In the letter, the community condemned Thae for making critical comments of North Korea's human rights at a recent seminar at the National Assembly. "You only made remarks that hinder peace and unification (of the two Koreas) during the seminar," the community wrote. "Please stay calm and don't stand in the way toward peace and unification."According to reports, Thae decided to cancel "at the last minute" after discussing the issue with his security guards."We were told from Thae's side that it would be difficult for him to attend the event because of those who would stage a rally calling for Thae's arrest," an event organizer was quoted as saying in a report.Earlier, Thae complained about the government's sluggish response to threats to defectors critical of the North.